Troubleshooting
SiBE04-624_B
104
Service Diagnosis
2.19 Signal Transmission Error on Outdoor Unit PCB
Error Code
U7
Method of Error
Detection
Communication error between microcomputers mounted on the outdoor unit PCB.
Error Decision
Conditions
When the data sent from the microcomputer of the inverter can not be received successively
for 15 seconds, the unit shuts down.
Error counter is reset when the data from the microcomputer of the inverter can be
successfully received.
Supposed
Causes
Defective outdoor unit PCB
Troubleshooting
(R18133)
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
Does the error repeat?
NO
Check blinking interval of LED 5.
Is the interval 0.5 sec.?
(same as LED A)
YES (0.5 sec. interval)
5 V ± 0.5 V
Check the voltage between +5V
and GND .
YES
NO
YES
Power on again.
NO
(0.2 sec. interval)
Replace the outdoor unit
PCB.
Replace the outdoor unit
PCB.
The cause seems to be an
external factor other than
failure of the outdoor unit
PCB.
Monitor in long term.